Area Forecast Discussion
Issued by NWS Pueblo, CO
Issued by NWS Pueblo, CO
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
588 FXUS65 KPUB 040543 AFDPUB Area Forecast Discussion National Weather Service Pueblo CO 1143 PM MDT Fri May 3 2024 .KEY MESSAGES... - Severe thunderstorms will be possible later this afternoon and through the evening over the eastern plains. Wind gusts in excess of 60 mph, hail of up to 2 inches in diameter possible. A brief landspout or weak tornado cannot be ruled out. - A cold front will move through later this evening over the plains, with colder temperatures and gusty winds out of the northeast behind it. - General thunderstorms are possible elsewhere over the plains and over the eastern mountains, which will continue throughout the night for some areas, mainly over the far southeastern plains and Raton Mesa area. - Frost conditions will be possible tonight over El Paso County. - Increasing winds and fire danger early next week with a trend towards cooler and wetter conditions for late week. && .UPDATE... Issued at 815 PM MDT Fri May 3 2024 Have allowed the Red Flag Warning to expire this past hour, as winds continue to diminish and RH values improve. Have kept the Severe Thunderstorm Watch in effect this evening, as additional strong to severe storms remain possible. Southward moving strong cold front will encounter stronger south southeast winds along with dewpoint air still in the 40s to low 50s. This should allow at least isolated thunderstorm development, some of which will still be capable of producing hail to the size of quarters and wind gusts to 60 mph. Highest chances for this to occur late this evening, is along and southeast of a Kim to Lamar line. Any remaining development should be southeast of the CWA by around the midnight time frame. && .SHORT TERM /THROUGH SATURDAY/... Issued at 224 PM MDT Fri May 3 2024 Currently and through tonight... A major shortwave trough is continuing to approach the region, with the development of a lee-side low by later in the afternoon as the trough axis moves overhead. As this pushes out over the plains a slightly deepens, it will force a cold frontal boundary to move down from the north over the plains. A dryline is going to establish itself, where there are currently 50+ dewpoints over northeastern New Mexico that will make their way up over far southeastern Colorado later this afternoon, this will act as a triggering mechanism for pre-frontal convective development once the cap completely erodes and the convective temp is achieved, which may turn severe given the higher dewpoints and thus increased low-level instability. An increasing low-level jet out out of the southwest will also increase shear necessary for further updraft enhancement and may allow for severe thunderstorm development for the next couple of hours, mainly over Las Animas County and east. A consensus of the latest high res guidance has the front beginning to move over northern El Paso County by as early as 7 to 8 PM, and then push through the CWA by around midnight. The timing of the front could be sooner, depending on whether or not if it is accelerated by outflow from convection that develops along and behind the boundary. Currently, there have already been multiple cells that have initiated over this area, which will likely continue to develop as the lower levels further destabilize by early evening as the low- level jet increases with effective shear of a magnitude around 30 kts or greater. MLCAPE is also going to increase to 1000 J/kg or greater, especially over Prowers and Baca counties, mainly after 4pm. With this, the potential for thunderstorms becoming severe will increase going into the later afternoon/early evening hours, especially anywhere from La Junta to Kim, and eastward. There are also going to be general thunderstorms possible over the eastern mountains and along portions of the I-25 corridor, mainly south of Pueblo County, that will continue to move off to the east-northeast after development. Dry conditions, with low relative humidity values and gusty southwesterly winds will continue to keep fire weather conditions going until around 9 PM in the San Luis Valley, although RH values should recover enough to allow the Red Flag Warning to come down by this time. The latest CAM guidance and HREF helicity tracks favor development of stronger, and possibly severe, cells over Prowers and Baca counties between 6 to 8 PM. In addition, the latest HRRR model also puts the development of a cell over Baca, with easterly winds turning into it at 00Z (7 PM), suggesting that there could be increased SRH values right around this time and possible supercell development, with the capabilities of producing a brief landspout and/or weak tornado. It also has something similar right around the same time over Prowers County, as well as the development of a strong cell right on the edge of northeastern Kiowa County. The NAM4km Nest has also been persistent with the past couple of runs of having a pre-frontal cell develop with over the northwestern Baca County/Bent County and then move into Prowers County right around the same time. Colder air advection moving in behind the frontal passage that will occur later this evening will allow for temperatures to continue to drop, especially as skies further clear. This will allow for temperatures over El Paso County to drop to near, or below, the freezing mark. Due to this, there will likely be some areas of frost. Stratus will also develop, mainly along the I-25 corridor from Pueblo County and northward to Monument. There could still be some showers, and possibly a thunderstorm, continuing into the early morning hours of tomorrow. As the lower levels continue to stabilize, showers will also continue to diminish and move southeastward and out of the CWA towards daybreak. Lows will bottom out into the 30s to low 40s over most of the plains, and generally in the upper teens and 20s for high country. Tomorrow... With colder air already in place, it will be more stable over the plains, and notably cooler. Highs will likely remain in the 60s over a majority of the plains and San Luis Valley, and only 40s to 50s for the higher terrain. With residual moisture, and increasing mid- level flow out of the southwest coupled with orographic lifting, there will be showers and thunderstorms developing in the afternoon hours over the higher terrain. This will get pushed out over the plains by later in the day. These should be more of your "garden variety" type thunderstorms, although there could be an isolated storm or two that is on the stronger side. With more of an inverted- v profile, some of these storms may result in some gusty outflow winds to 50 mph or greater, and there could be hail up to 1/2 inch with the stronger storms. The plains will likely remain dry with more stable air in place, although a few of the showers/storms could move out over the adjacent plains and portions of the I-25 corridor. -Stewey && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... Issued at 224 PM MDT Fri May 3 2024 Weak wave in southwest flow ejects across CO Saturday evening with cool stable upslope flow maintaining across the plains. A few showers may drift off into the adjacent plains but they should diminish as the move off the mountains into the more stable airmass. Have trimmed eastward extent of pops into the I-25 corridor during the evening. Showers and thunderstorms will diminish across the mountains behind this feature in the evening but could regenerate across the far eastern plains late Saturday night as the low level jet increases. Any isolated nocturnal convection will have limited CAPE resulting in some weak elevated showers/thunderstorms into Sunday morning. Temperatures then rebound for Sunday as southerly flow increases across the region ahead of the next upper low moving into the Great Basin. Will need to watch the San Luis Valley for potential Critical Fire Weather conditions until green up occurs. For now, coverage and magnitude looks too limited with RH the most limiting factor for Sunday. Showers and thunderstorms will redevelop across the Continental Divide as moisture increases ahead of the upper low. Out east it remains largely dry. Will need to monitor the position of the dry line but for now dew point return and CAPE looks limited with little to no initiation along the boundary in the afternoon. Upper low lifts out across northern CO Sunday night and Monday. With the more northern storm track, this puts southern CO under the dry and windy region of the storm. Latest NBM shows potential for wind gusts greater than 50 mph in the 70-90+ percentile, especially along and south of highway 50 Monday morning. We could be looking at brief near high wind potential Sunday morning if we can mix 50-60 kts down to the surface Sunday morning as the cold front moves through. In spite of the cool down, it will be very dry and likely a critical fire weather day for the San Luis Valley and southern portions of the southeast plains where fuels are still critical. The Continental Divide will pick up some snow Sunday night through Monday morning with a diminishing trend in the afternoon as the storm ejects to the northeast. The windy and mostly dry pattern continues for Tues and Wednesday with temperatures rebounding. Then we trend towards a cooler and potentially wetter pattern as low pressure stalls out over the western U.S. and a cold front moves through the plains bringing post frontal upslope flow Thurs into next weekend. Thursday could potentially be the coolest and wettest day with snow levels dropping to around 7000 feet across the southeast mountains. Still some details to resolve on the track and strength of the low which will drive the degree of upslope and precipitation amounts. EC is weaker with the upper low and magnitude of upslope, and therefore has less QPF/snow. Probabilities of greater than 3" of snow accumulation is less than 30 across all but the central mountains from the National Blend of Models. Central mountains fair a little better with probabilities for up to 6 inches up to 40%. This will bear watching as details become more certain. -KT && .AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 1134 PM MDT Fri May 3 2024 VFR conditions with mainly dry weather is expected across the TAF sites this forecast period. While conditions remain clear at ALS this morning, low stratus will likely build back towards PUB and COS early this morning. Ceilings are currently VFR and expect them to remain that way as they move across the terminals. If ceilings were to fall to MVFR, think COS would have the higher chance of observing these lower ceilings. Once again, think this is a low chance though. Any lower ceilings clear out by early to mid morning, with clearer skies expected for much of the day. Will see the lighter winds in place this morning increase during the day, with southeast winds at COS and PUB and south southwest winds at ALS. Highest gusts at all sites look to be in the mid 20 kt range. Scattered showers with isolated thunderstorms will develop over the higher terrain this afternoon, and think conditions will remain dry at all sites. With a slightly higher chance for a shower at ALS, have included a VCSH during the afternoon time frame. && .PUB WATCHES/WARNINGS/ADVISORIES... Frost Advisory until 9 AM MDT Saturday for COZ084-085. && $$ UPDATE...RODRIGUEZ SHORT TERM...STEWARD LONG TERM...KT AVIATION...RODRIGUEZ